<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
      .left {
        float: left;
        width: 100px;
        height: 200px;
        background-color: brown;
      }

      .right {
        float: right;
        width: 200px;
        height: 200px;
        background-color: skyblue;
      }

      .main {
        margin-left: 120px;
        margin-right: 220px;
        height: 200px;
        background-color: greenyellow;
      }
  </style>

</head>
<body>
    <div class="container">
        <div class='left'></div>
        <div class="right"></div>
        <div class="main"></div>
    </div>
</body>
</html>